Miniature bias-tee networks integrated in micro-coaxial lines

This paper presents miniature broadband bias tee networks designed in a micro-coaxial environment. The process for fabricating the air-filled coaxial lines by wafer-scale sequential metal deposition, referred to as PolyStrata™, enables hybrid assembly of surface-mount components such as inductors and capacitors, enabling DC blocks and RF chokes. The microcoaxial lines can be designed with a wide variety of characteristic impedances fabricated in the same process, allowing for easier matching to active devices such as power amplifiers, which typically have low input and output impedances. In this paper, bias tee networks in both 12Ω and 50Ω environments are demonstrated with 0402 capacitors and 0402 inductors, as well as with monolithically integrated coil inductors. The measured performance shows 14 dB insertion loss from 4 to 16GHz with a better than 0.75 dB return loss and up to 5A power handling in a circuit with a 8.3mm² footprint.